From 69466466ce889cd2cbc8cda9ff1c6083f48cc7f9 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 24 Feb 2012 11:55:01 +0000 Subject: [PATCH] x86-64: Improve insn scheduling in SAVE_ARGS_IRQ In one case, use an address register that was computed earlier (and with a simpler instruction), thus reducing the risk of a stall. In the second case, eliminate a branch by using a conditional move (as is already done in call_softirq and xen_do_hypervisor_callback). Signed-off-by: Jan Beulich Link: http://lkml.kernel.org/r/4F4788A50200007800074A26@nat28.tlf.novell.com Reviewed-by: Andi Kleen Signed-off-by: H. Peter Anvin --- arch/x86/kernel/entry_64.S | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index a20e1cb9dc87..211b2e1683f1 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -319,7 +319,7 @@ ENDPROC(native_usergs_sysret64) movq %rsp, %rsi leaq -RBP(%rsp),%rdi /* arg1 for handler */ - testl $3, CS(%rdi) + testl $3, CS-RBP(%rsi) je 1f SWAPGS /* @@ -329,11 +329,10 @@ ENDPROC(native_usergs_sysret64) * moving irq_enter into assembly, which would be too much work) */ 1: incl PER_CPU_VAR(irq_count) - jne 2f - mov PER_CPU_VAR(irq_stack_ptr),%rsp + cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp CFI_DEF_CFA_REGISTER rsi -2: /* Store previous stack value */ + /* Store previous stack value */ pushq %rsi CFI_ESCAPE 0x0f /* DW_CFA_def_cfa_expression */, 6, \ 0x77 /* DW_OP_breg7 */, 0, \ -- 2.39.5